In recent years, a self-luminous display device using a light emitting element (EL element) employing an electroluminescence (hereinafter referred to as “EL”) phenomenon has been developed as a display device instead of a liquid crystal display device.
A display device including an EL element can emit light at low voltages. The EL element is a self-luminous element, and therefore has a wide viewing angle and high viewability. Further, the EL element is a thin film-form completely solid element, and is thus garnering attention from the viewpoint of saving space, portability, and the like.
The EL element has a configuration in which a light-emitting layer containing a luminescent material is interposed between a cathode electrode and an anode electrode. The EL element emits light by using the release of light during the deactivation of excitons that are generated by injecting electrons and holes into the light-emitting layer and causing recombination.
The light-emitting layer of an EL element is mainly formed using vapor deposition techniques, such as vacuum vapor deposition. Techniques for forming of a full-color organic EL display device using such vapor deposition can be broadly divided into a white CF (color filter) technique and a separate-patterning technique.
The white CF technique is a technique in which a white light-emitting EL element and a CF layer are combined, and a luminescent color is selected at the subpixel level.
The separate-patterning technique is a technique where separately patterning vapor deposition is carried out for each luminescent color using vapor deposition masks. Generally, subpixels constituted by red (R), green (G), and blue (B) EL elements, arranged on a substrate, are selectively caused to emit light at desired brightnesses using TFTs, and an image is displayed as a result. Banks (partitions) defining light emitting regions in the subpixels are provided between EL elements, and the light-emitting layers of the EL elements are formed in openings of the banks using a vapor deposition mask.